Fuse link



Nov. 7, 1933. A. G. STElNMAY-ER FUSE LINK Filed Nov. 8, 1929 Patented Nov. 7, 1933 UNITED. sures PATEN OFFICE FUSE LINK Alwin G. Steinmayer, Milwaukee, Wis., assignor' to Line Material Company, South Milwaukee, 7 Wis., a corporation of Delaware Application November 8,1929. Serial No. 405,577

6 Claims. (c1. 200-435) This invention relates to fuse links.

been found extremely difiicult to make a low amperage fuse link which is mechanically strong and which also may be made of a uniform ca; pacity. f 1

When it is considered that in the high voltage circuits the fuse links have to be relatively long, it will be seen that the small diameter of low amperage fragile.

Several attempts have been made to overcome this difficulty, among which'may .be mentioned the enclosing of the fuse link in insulating tubing, commonly known as spaghetti tubing.

This type of fuse has been found to have a oertain choking effect which very often causes the fuse to clear too rapidly, which results in the fusing of an insufiicient length of the fuse link. The result of this is that a leakage occurs between the ends of the fuse link adjacent the fused portion, and this leakage very oftenproduces spitting or'other radio interference. In

addition to this, there is a slow carbonization which takes place'which frequentlyv finally results in burning through the fused cartridge] In additionto these defects where the low amperage fuse is enclosed by the reinforcing material, the resulting structure is relatively stiff and is difiicult to. expel ev'en'if the tubing enclosingthe fuse link burns completely through at the time of the fusing. Further'than this, inasview by the enclosing insulating material, or

visible signs thereof, sothat the fuse linkmust necessarily be tested before it'can beused.

Inaddition tothe defects noted above, been the common practice to solder one end at least of the fuse link toa terminal .clip or cons tact member. This process of soldering usually reduces the section of thefuse link immediately adjacent the clip and thus varies the capacity of the fuse and makes the capacity other than that for which the fuse is intended. In addition to this, certain chemical changes take place 'a'cl-Q This invention is designed to overcome "the. de

fects noted above, and objects of this invention fuses v renders them particularly struction which does not require soldering or any i v I I I the, necessity for testing the fuse link before in-; spaghetti tubing, it is apparent that. the fuse, links are very often broken withoutgiving any 'soever after the fuse blows, in which there can- Thus there is very frequently a g j are to provide a novel form of fuse link which In fuse links as heretofore constructed, it has may be made in any desired size, even in-the very small orlow amperage sizes, and which is reinforced throughout its length so that, although the fusible portion thereof may be relatively fragile, nevertheless the composite structure forming the fuse link is very strong and is not easily damaged.

Further objects are to provide a low amperage fuse link which has a combustible, easily destroyed cord or core upon which the fusible-element itself may be wound or otherwise carried,

in which the reinforcing portion is very flexible and is combustible and is easily destroyed when the fuse blows, so that it'may be very readily expelled to thus insure complete separation and wide spacing at the gap where the fusing occurs. Further objects are to provide a fuse link conchange in' the standard terminal arrangements, but which is so made that a simple type of metal clip cooperates with the end of the fuse in a manner to insure complete and adequate contact between the terminal member; and the fusible element, andwhich is so made that a uniform capacity is; obtained at all times, so that there is absolute certainty as to the capacity fuse. l I 7 Further objects are to provide a construction of fuse link in which'the fusible element is visiof the.

ble throughout its length, and therefore any I break inthe fusible element may be visually demuch as the fuse link is completely hidden from' tected with theutmost ease, thus dispensingwith sertion inthe fused cartridge. I v Further objects are, ,;to providea fuse link.

whichis so madethat itwill have a reduced section preciselydetermining the value of current it has at which-the fuse will blow, and which is of; sturdier construction throughout the remainder of its length, thereby minimizing the chance of damage in handling the fuse. Further objects are to provide a fuse structure in which there will be no radio interference what-.

be-no slow carbonization of -any portion of the. fuse structure, and in which complete expulsion of the fuse link is assured.

Embodiments of the invention are shown in the accompanying drawing, in which: 7

Figure 1 is a side elevation of the fuse strucvtu re, showing-the fuse link in place.

Eigure2 is 'an enlarged fragmentary view, of the upper portion of the fuse link, with parts in section.

- tion to this, it is possible to use a single strip or strands is wrapped over the ends of the strands Figure 3 is a top view of the structure shown in Figure 2, with a part of the upper member of the clip broken away.

Figure 4 is a view from the under side of the upper clip, such view showing a modified manner of attaching the upper end of the fuse link.

The fuse link may be used with a number of diflerent types of fuse structures, but for the sake of illustration, it has been shown as used with an expulsion type of fuse cartridge.

Referring to Figure 1, it will be seen that the cartridge comprises an elongated insulating tube or member 1 which has an upper terminal mem ber 2 of metal secured thereto and provided with a central aperture 3. A metal cap 4 is screwthreaded to the upper end of the terminal member 2. The tubular insulating cartridge 1 carries a lower terminal member 3 which may be provided with a beveled portion 4 cooperating with a similar beveled face of a ring nut 5. A slot 6 may be formed in the threaded portion of the lower terminal member, as illustrated in the drawing, to receive the lower end of the fuse link.

The fuse link comprises a flexible body portion 7, preferably a combustible cord, upon which the fusible element or fuse wire or strip is wound. It is preferable to provide a reduced portion 8 adjacent the upper end of the fuse link, and an enlarged or multiple-stranded portion 9 for the remainder of the fuse link, so as to predetermine the point at which the fuse will first rupture. This is readily accomplished by providing several strands of the fuse wire for the lower portion of the fuse link and continuing one strand only to the upper end of the fused link, as shown most clearly in Figure 2. Obviously, the capacity may be varied either by varying the diameter or size of the fuse wire, or by varying the number of strands in the reduced section. In the form shown, three strands have been employed for the major portion of the fuse link, as indicated at 9 in Figure 2, and a single strand has been employed for the reduced section, as indicated at 8 in such figure. Very clearly, it is within the province of this invention to use, for instance, fouror five strands in the main section of the fusible element and two or more strands in the reduced section, as long as the reduced section has in reality a lesser number of strands than the major portion of the fusible element. In addistrand for the fusible element, and to reduce a portion of this strip for the reduced section. It is to be noted from Figure 2 that the portion of the fusible element having the lesser number of from the portionhaving the greater number of strands, thus binding these ends to the core.

With the low amperage fuse links, the fusible element is extremely delicate. This, however, does not interfere with the free handling of a fuse link constructed in accordance with this invention, as the relatively delicate fusible element is spirally wound or otherwise carried exteriorly of the cord or combustible core '7. The

core itself furnishes the mechanical strength while in no way interfering with the flexibility of thecomposite structure and therefore in no way interfering with the free and complete expulsion of the fuse link. Further, due to the construction employed, it is apparent that the fusible element may be easily inspected, as all portions thereof are visible and any break is readily detected without resorting to any test whatsoever.

No soldering is employed in joining this fuse to its terminal clip. Instead, a terminal clip of very simple construction is provided which consists of a small circular metal disc or body portion 10, preferably provided with a central aperture through which the fuse link is passed. The end of the fuse link may be looped back and forth, as indicated in Figure 3, and an upper clip or member 11 is positioned above this looped portion. This upper clip is also formed of metal and is preferably provided with a pair of downturned ears 12 which pass into apertures in the disc 10 and are bent over or clinched, as indicated at 13 on the under side of the disc 10.

It will be seen that the upper portion of the fusible link contacts at a number of points with the metal contact clip so that there is absolute assurance of a good contact Without any necessity whatsoever for soldering.

In addition to this, it is a very simple matter to slip the fuse downwardly into place through the aperture 3 in the upper terminal member 2 of the fuse cartridge. The lower end of the fuse link is then looped back over the bottom of the cartridge and locked in place against the lower contact member 3 by means of the clamping nut 5. Thereafter the end cap or upper cap 4 is screwed into place and binds the contact clip, which encloses the upper end of the fuse, tightly against the upper contact member 2. This insures secure and adequate electrical contact for the fuse link.

It is to be noted that the inturned lower ends 13 of the ears 12 aid in positioning the terminal clip, as these inturned ends fit within the opening 8 of the upper terminal member 2, as shown in Figure 1.

When the fuse is overloaded, the fusible element will melt at its reduced portion, and the sudden generation of heat and gases will completely expel and destroy the fuse link structure.

It is apparent therefore, that no radio disturbance and no slow carbonization due to leakage can occur after the fuse blows.

It is apparent that the upper end of the fuse link may be secured to the terminal clip in other ways than that illustrated in Figure 3. For example, as shown in Figure 4, the upper end of the fuse link may be wrapped around the prongs or cars 12 of the upper member 11 of the terminal clip. It is to be understood that the terminal 'clip secured to the upper end of the fuse link may be employed with a fuse link which does not have the reinforcing cord and that, when so used, it will insure adequate and satisfactory contact for the upper end of the fuse link without the necessity of soldering. c

It will be seen that a novel form of low amperage reinforced fuse link has been provided by this invention which is eminently practical and may be most easily produced, which may be secured in place without soldering and with the assurance that not only good contact is made, but also no variation in the capacity of the fuse is produced.

It will be seen, further, that a very flexible fuse link has been provided which is freely and completely destroyed and expelled and which, although freely flexible, may be readily handled without damage to the fuse link.

Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

1. A fuse structure comprising a fuse link and a terminal clip, said terminal clip comprising a disc-like body portion having an aperture therethrough through which the end of the fuse link may be freely passed during assembly, and having an upper member held to the body portion and holding the upper end of said fuse link clamped to said body portion, said upper member having a portion bent around said lower member to clamp said members tightly against said fuse link.

2. A fuse structure comprising a fuse link and a terminal clip having a disc-like, apertured body portion, said fuse link extending through the aperture in the body portion, said terminal clip having a member provided with prongs clampedto said disc-like body portion and binding the end of said fuse link between said member a terminal clip, said terminal clip having a body portion provided with an aperture through which said fuse link is threaded, said terminal clip having an upper member binding the fuse link against the body portion, said upper member having a pair of prongs extending through said body portion and clinched against said body portion.

5. In a fusev structure, the combination of a fuse cartridge having a terminal member provided with an end capscrew-threaded thereon, said terminal member having an aperture therethrough, and a fuse structure comprising a fuse link extending through said aperture, and a terminal clip having'two metal portions clamping the end of said fuse link between them and adapted to be forced into binding engagement with the fuse link and with the terminal member when said cap is screwed into place.

6. A composite fuse link comprising a reinforcing core, and a fusible member wound thereon and comprising a plurality of strands, one portion of said fusible element having a greater number of strands than the other portion thereof, the portion having the lesser number of 1 strands binding a plurality of strands of the other portion to said core. I

. ALWIN G. STEINMAYER. 

